Ah, I couldn't understand why you were asking. Now I see we were talking about different mileages. To display total miles on the car just cycle through the different readings with the Trip button, I think it has Trip A, Trip B, Miles to go before you need gas, and total miles on the car. Or just watch the display when you turn the car off it always comes up for a few seconds before everything goes dark.
Simple solution here ... use a spreadsheet to track your mileage (and other car expenses). If you don't know how to do that, get a notebook and a calculator. You can fill it out and calculate the numbers while you fill up.
